The rains finally came to the drought-stricken Southeast. For days in September 2009, the city of Atlanta was drenched by recurring rainfall. Falling at a rate of one to two inches per day, rain accumulations of more than 11 in were logged during an 8-day period. 

Normally, a region experiencing a long drought and severe water-use restrictions would welcome the liquid gold precipitation. However, it was too much of a good thing, and the massive runoff contributed to severe flooding and flash flooding. “This event was considered a 500-year flood,” recalls Dan Morgan, president/owner of Marietta, Ga.-based Metro DKI, a restoration company in operation for more than 40 years.

The Chattahoochee River in northeast Atlanta crested at a height not seen in 90 years. River water flooded entire neighborhoods and businesses, and it inundated a nearby lake surrounded by million-dollar homes. As the lake’s level rose, water crept ever so slowly toward the posh houses and eventually filled the lower floors with more than three feet of water. As the lake slowly receded, the race was on to quickly restore the homes to preflood condition.

Preventing Secondary Damage
“This house was under water for approximately 48 hours,” comments Morgan, referring to one Atlanta home Metro DKI was in the process of restoring. The dirty water forced drywall removal to the studs nearly half way up the first floor walls. As soon as the damaged materials were removed, Metro DKI’s crew focused on drying the structure. “Our primary goal was to salvage the rest of the house and prevent mold,” he adds.

Crews sealed off the second level of the 6,500 ft² home and concentrated their efforts on the 2,600 ft² lower level and crawl space. Ductwork from the MC 5200 – one supplying dry, heat-conditioned air to and the other extracting moisture laden air from the structure – was concentrated on the first floor to quickly dry the structure.

“The MC 5200 channels outside air, heated and conditioned to a 5 to 12% relative humidity level, into the structure,” explains Ken Cannella, product manager for Wacker Neuson Climate Control equipment. “Our drying system pumps hot, dry air into the structure to raise the temperature of material inside and release trapped moisture. The unit can be effectively used in the warm, humid summer months and cold, dry winter months.”

To dry the house’s crawl space, Metro DKI employed an indirect fired Cub 200 air heater from Wacker Neuson Climate Control. The Cub 200 delivers 146,700 BTU/hr heat output and generates 1,300 CFM airflow.

In addition, 30 air movers helped to circulate the warm, dry air throughout the first floor of the house. “We were able to create a horseshoe airflow effect, allowing the structure to be quickly dried,” says Morgan.

Even with ambient conditions during this October restoration application averaging 73% relative humidity and mid 70° F high temperatures, the MC 5200 quickly reduced the humidity inside the house. Morgan sees controlling humidity a key attribute of the MC 5200. “By the third day, our internal readings showed a 17% relative humidity at 100° F,” he says. The net result showed Metro DKI was able to completely dry down the house and crawl space in just over two days with the Dryvex™ MC 5200 open drying system and Cub 200 heater.

Drying Time Cut Nearly in Half
The historic Atlanta flooding kept Metro DKI extremely busy. In addition to the 6,500 ft² house dried with the Dryvex™ MC 5200, the company restored a second, smaller home right across the street, which was also flooded with 3 ft of water. For this 5,700 ft² home, Metro DKI used a 5,000 CFM desiccant drying system for dry down.

Unfortunately, Metro DKI’s 5,000 CFM desiccant drying system and air movers took longer to dry this structure. Since desiccant systems do not generate the heat that is required to absorb large quantities of water, the company’s crews were on that job a total of 4 full days to complete dry down. According to Morgan, “The MC 5200 system dried the larger house in about half the time as a desiccant system.”

Cannella explains why the Dryvex™ open drying system is capable of drying a structure faster. “The hotter and drier the surrounding air becomes, the faster moisture will release from saturated materials and turn from liquid to vapor,” he says. “That is the basis for our Dryvex™ MC 5200 convection system.”

Quickly drying a structure equates in less of a chance for secondary damage and lower equipment and labor expense. “We had equipment cost for an additional 2 days, so it was also more expensive using the desiccant drying system,” summarizes Morgan.

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